This invention relates to a feed mechanism, and more specifically to a feed mechanism specifically adapted for user in machinery for the automated manufacture of tin boxes.
Automated tin box manufacture is accomplished by juxtaposing several different pieces of machinery said providing transfer means therebetween tin boxes can be manufactured is a vast number of different shapes and sizes and accordingly a single piece of machinery is required to be sufficiently versatile to enable manufacture of tin boxes in a large number of said shapes and sizes. It will be understood by those skilled in the art that the machinery need has a number of different components which can be exchanged to facilitate the manufacture of different boxes and currently the length of time taken to exchange all these various components to enable a particular set of machines to manufacture a different box shape can be up to an entire day. The invention hereinafter set forth, and slap set forth is our co-pending applications have as their object the reduction of this time. Any reduction achievable is the xe2x80x9cchangeoverxe2x80x9d time is especially desirable when it is considered that tin box production rates using the machinery described hereinafter may reach 40 per minute.
Tin boxes can contain a wide variety of different goods, such as bottles, chocolates, biscuits, tea, coffee and the like. Manufacturers of such products commonly consider the containment of their product in tins because of the rigidity and durability which the sheet steel, from which such tins are commonly made, provides. Additionally, the containment of a product in a tin box may also suggest that the product therein is of a certain quality, especially as ornate and detailed print effects can be obtained on the surface of the metal plates from which the tin boxes are manufactured. Such effects cannot be achieved, or are achieved snip to a much lesser degree by the containment of products in cardboard cartons or receptacles of plastics materials. A tin box in which such a product as contained has the further advantage of being reusable to contain other household items such as screws, nuts bolts, pencils and pens, etc. after the product originally contained therein has been consumed or otherwise utilised.
The various separate machines required in the manufacture of tin boxes are an xe2x80x9cAutomatic Curling Notching and Beadingxe2x80x9d machine, a xe2x80x9cbodymakerxe2x80x9d, a xe2x80x9cround and irregular seamerxe2x80x9d, and an xe2x80x9cend feederxe2x80x9d, each of which has a specific task to perform during the process of tin box manufacture. Each of these is now described.
The first stage in the process of automated tin box manufacture is the profiling of a simple sheet steel, and generally rectangular blank from which the walls of the tin box are ultimately constituted. The blank is fed through an xe2x80x9cAutomatic Notching, Curling and Beadingxe2x80x9d machine, referred to hereinafter as an ANCB machine. This machine consists of a plurality of consecutively drives rollers disposed both above and below the blank as it passes therebetween each of said rollers performing a forming step on the blank. The particular profile of each blank as it exits the ANCB machine depends on the ultimate shape of the tin, but in general the blank is substantially flat with the exception of a hem provided parallel with one of the longer edges of the blank and proximate thereto, a bead is provided on one of said longer edges, a partial curl is provided around the alternate longer edge, and a pair of hooks oppositely disposed with respect to one another on the shorter edges. Additionally the ANCB machine has cutting means which catch the corners of the blank to preclude any interference effects which may be caused by said corners either when the blank is profiled and provided with the hooks along its shorter edges, when it is formed into the cross-sectional shape of the tin box, or when wrapped around and attached to the base of said tin box.
The hem provides a surface behind which the beaded lip of a tin lid can engage to inhibit the removal of a lid separately formed and applied around the uppermost edge of the tin box, the bead is provided to hide the sharp longer edge of the blank which ultimately forms said uppermost edge of the tin box, the partial curl on the alternate longer edge of the blank is provided to facilitate the attachment of the blank, after same has been formed into the desired cross-sectional shape, to the base of the tin box, and the hooks provided along the shorter edges of the blank facilitate the connection of said edges to one another after the forming operation. In practice, the bodymaker may be responsible for the formation of the hooks on the shorter edges of the blank to facilitate connection of said edges to one another.
The profiled blank is then fed from the ANCB machine into a bodymaker by a feed mechanism forming an integral part of the bodymaker which generally comprises a pair of reciprocating feed bars whose motion is best described is being that of a xe2x80x9cwalking beamxe2x80x9d is conjunction with xe2x80x9cdisappearing guidesxe2x80x9d which simultaneously urge the profiled blank towards and over a forming mandrel and precisely align said blank thereon. The disappearing guides are rotated away from the blank when it is held in contact with the uppermost portion of the mandrel, which is generally of similar shape to the desired cross-sectional shape of the tin box to be manufactured, by a mandrel clamping arrangement. The removal of the disappearing guides (so-called because they are retracted and seem to xe2x80x9cdisappearxe2x80x9d within the machine during the forming of the blank ground the mandrel) allows a pair of forming wings pivotally connected together and disposed above the mandrel to rotate about their pivot and form said blank, which is at this stage still substantially planar, around the said mandrel. The forming operation performed by the wings also constrains the oppositely disposed hooks on the shorter edges of the blank to interlock on the underside of the mandrel whereupon a second forming tool compresses the metal of the blank in the interlocked region to form the vertical team within the wall of the tin box. During all forming operations the blank is clamped against the upper surface of said mandrel by said mandrel clamping arrangement.
This invention is specifically concerned with the provision of a novel feed mechanism.
The feed mechanism currently used to transfer the pressed blanks from the ANCB machine through the bodymaker is now described. The profiled but substantially planar blanks exit the ANCB machine onto a pair of pivotable drop rails which both guide and support the blank as a travels until it contacts a stopping member. The pivotable guide rails are actuated with a predetermined frequency which corresponds to the rate at which the profiled blanks are fed into and exit the ANCB machine and also to the rate at which the said blanks can be fed through the bodymaker. On acruation, which is typically effected by a cam arrangement, both a drop rails swing outwardly and away from each other such that the bank supported thereby falls onto a pair of parallel feed bars disposed with a feed table, said feed bars reciprocally traveling in a xe2x80x9cwalking beamxe2x80x9d type manner in a direction perpendicular to the direction of travel of the blanks exiting the ANCB machine.
Each of said feed bars is provided with a plurality of spring loaded pawls which engage behind one of the edges of the blank as it tests thereon of on the feed table, and these pawls urge the blank through the bodymaking machine.
The feed table on which the blank travel in generally symmetrical about an axis parallel to the direction of travel of the blanks thereon and is substantially hollow to allow the feed bars and driving machinery to operate unhindered therein. The feed bars are rigidly secured with bolts or the like to a feed bar transport supported end freely slidable on horizontal guide rails whose length is marginally less than the length of the feed mechanism. Although the feed bars are sufficiently separated to provide a certain degree of stability for the blanks being transported thereon into the bodymaker, the requirement for precision placement of the blanks on the mandrel of the bodymaker is such that stationary guide means are also required at each side of the feed bars to ensure that the orientation and positioning of the blank on said feed bars is correct. Accordingly, such guide means are rigidly secured to the feed table and come into contact with the edges of the blank which are perpendicular to that behind which the pawls are engaged.
As mentioned above there are a plurality of spring loaded pawls provided on each feed bar and in general there are three pairs of pawls, the pawls of each pair being disposed a predetermined distance from an end if the particular feed bar which is dependent on the length of travel of the said feed bars and also on the size of the blank supported thereby. The purpose of providing three pairs of pawls is to allow for three separate blanks to be simultaneously moved by said feed bars, each blank being at a different position thereon and being moved by a separate pair of pawls engaged behind one of the edges of said blank. After the feed bar has reached the extent of its travel in one direction and urged the blanks supported thereon towards and/or into the body forming tools of the bodymaking machine, the direction of travel of said bars reverses. The blanks do not however return to their original positions with the feed bars as the pair of opposite edges of said blanks an either side of and parallel with the feed bars frictionally engage the guide means which retain the blank is that position. Additionally the spring loading of else pawls, their profiled shape and their pivotable mounting within the feed bars allows said pawls to slide under the leading edge of the blanks retained in the guide means and springingly emerge in front of the opposite trailing edge with which the booked portions of the pawl can engage to urge said blank along the feed table.
Hence, the blanks are intermittently moved forward on the feed table and through the bodymaking machine on the reciprocating feed bars. It will now be understood that the timing of all the various machinery operations and transfers between separate pieces of machinery is critical in maximising the overall throughput of the machine. In practice, the timing of all the various operations and transport mechanisms is controlled by computer apparatus.
The blank feed mechanism described above is adequate for transferring blanks of a particular size and shape from the ANCB machine to the bodymaker, but as described above all those machines involved in the automated manufacture of tin boxes are required to be sufficiently versatile to accommodate blanks and bases of different sizes and shapes, and the feed mechanism described is severely disadvantaged in this respect. It will be appreciated that the feed bars must be capable of being displaced towards or away from one another within the feed table to permit the transfer of smaller or larger blanks and the position of the guide means on either side of the feed bars must also be capable of being altered. Furthermore, it is essential that each of these components can be rigidly secured to the transfer table and feed table respectively after movement to ensure continued precise operation of the transfer mechanism.
In current feed mechanisms an anvil is rigidly secured by bolts to either side of the transfer table and it is to said anvils that the feed bars are attached, also with bolts, and symmetrically of the transfer table. The anvils are provided with a plurality of attachment locations to allow said feed bars to be attached thereto at a number of different separations to allow for the transfer of blanks of different sizes thereon. The intricacy of the machinery surrounding the transfer table, anvils and feed bars makes the changeover process unavoidably time consuming,
Although the description provided hereinabove and hereinafter relates almost exclusively to feed mechanisms used to transfer profiled blanks through the bodymaker during tin box manufacture, it is to be pointed out that the feed mechanism of the invention has far wider application. Indeed it is considered that the feed mechanism hereinafter described may be used in any circumstance where bodies, blanks or the like are to be carried on a pair of supports whose separation distance is required to be occasionally altered to accommodate differently sized bodies.
It is an object of this invention to provide a feed mechanism having at least a pair of feed bars, the separation distance between which can be altered as required simply, quickly and efficiently without compromising the precision with which said feed mechanism must operate.
According to the present invention there is provided a feed mechanism comprising a stationary feed table within which is disposed a drives transfer table to which a first support means is attached, a further second support means being provided within, the feed table at a separation distance from said first support means, characterised in that first and/or second support means are connected by telescopic means whose extension can be altered and securely set.
Preferably, both the first and second support means are connected by telescopic means whose extension can be altered and securely set.
Preferably the support means are longitudinal feed bars which are parallel.
Preferably the transfer table is reciprocally driven and thus imparts reciprocal motion to the said first feed bar and concomitantly to said second feed bar through its telescopic connection with the first.
Preferably feed bars are provided with pawls which engage behind the bodies which the feed mechanism is adapted to move to move same when said reciprocating motion is in a forward direction, and which slide underneath the said bodies when said reciprocating motion is in a reverse direction.
Preferably the pawls are spring biased and can be depressed so as to be flush with the upper surface of the feed bars when sliding underneath the said bodies which are frictionally held along a pair of opposite edges and thus do not slide is the reverse direction with said feed bars.
Preferably the transfer table is provided with guide bars which extend perpendicularly to the direction of travel of said transfer table and towards and underneath the feed bars, and which are provided with location means to ensure the parallel orientation of said feed bars.
Preferably the connection of the telescopic means to the transfer table at one end of said telescopic means, and to the feed bars at their alternate ends is effected using rose bearings which allow a degree of play during the alignment process.
Preferably, the feed bars can be disposed at one of a number of distances from the transfer table, and further preferably each feed bar can be disposed in one of five different positions.
Hence, the motion of bodies to be transferred between one location and another by said feed mechanism is discontinuous and discrete as is required in automated processes which comprise a number of discrete steps, but the case, simplicity and speed with which the feed mechanism can be altered to accommodate blanks of different shapes and sites is drastically increased using the telescopic means as described above and hereinafter. When it is desired to change the separation of the feed bars, the rose bearings which connect the telescopic member and also the extension lock thereon are simply loosened, the feed bars are then lifted from one position and moved towards or away from the transfer table as required and dropped back into one of the alternate locations provided by the guide bars. The bearings and the extension lock of the telescopic members are then tightened to lock the feed bars in position.